The present invention is in the field of imaging systems. More particularly, the present invention provides an apparatus and method for removing a slip sheet from the top of a stack of printing plates.
A cassette is often used to supply a stack of unexposed printing plates to an external drum imaging system. Each printing plate may comprise one or more layers supported by a support substrate, and one or more image recording (i.e., xe2x80x9cimageablexe2x80x9d) layers such as a photosensitive, radiation sensitive, or thermally sensitive layer, or other chemically or physically alterable layers. Printing plates are available in a wide variety of sizes, typically ranging, for example, from 9xe2x80x3xc3x9712xe2x80x3, or smaller, to 58xe2x80x3xc3x9780xe2x80x3, or larger. The printing plates are normally supplied in stacks of ten to one hundred, depending upon plate thickness and other factors. Interleaf sheets, commonly referred to as xe2x80x9cslip sheets,xe2x80x9d are usually positioned between the printing plates to protect the emulsion side of the printing plates from physical damage (e.g., scratches), which could render a printing plate unusable for subsequent printing. The slip sheets are typically formed from a porous material, such as paper.
Many different techniques have been used to remove a slip sheet from the top of a stack of printing plates to provide access to an underlying unexposed printing plate. For example, a vacuum system employing a plurality of suction cups has been used to pick up and remove slip sheets. Unfortunately, applying a vacuum through suction cups to a porous slip sheet can cause both the slip sheet and the underlying printing plate to be lifted simultaneously.
The present invention provides an apparatus and method for removing a slip sheet from the top of a stack of printing plates.
Generally, the present invention provides an apparatus for removing a slip sheet from a surface of a printing plate, comprising:
a wing for covering an end section of the slip sheet, an air manifold coupled to an end of the wing, the air manifold including a plurality of orifices for directing streams of air along an underside of the wing to lift the end portion of the slip sheet off of the printing plate and toward the underside of the wing, a plurality of idler rollers rotatably mounted about the air manifold, and a clamping bar mounted to the wing for selectively pinching the lifted end section of the slip sheet against the underside of the wing, thereby capturing the slip sheet.
The present invention further provides an apparatus for removing a slip sheet from a surface of a printing plate, comprising:
a wing having first and second rotatably coupled sections, a wing drive system for laterally displacing the wing to position the second section of the wing over an end section of the slip sheet, an air manifold coupled to an end of the second section of the wing, the air manifold including a plurality of orifices for directing streams of air along an underside of the second section of the wing to lift the end portion of the slip sheet off of the printing plate and toward the underside of the second section of the wing, a plurality of idler rollers rotatably mounted about the air manifold, and a clamping bar for selectively pinching the lifted end section of the slip sheet against the underside of the second section of the wing, thereby capturing the slip sheet.
The present invention also provides a method for removing a printing plate from a surface of a printing plate, comprising:
providing a wing having an air manifold, wherein the air manifold includes a plurality of orifices, and wherein a plurality of idler rollers are rotatably mounted about the air manifold;
displacing the wing over an end portion of the slip sheet;
displacing the idler rollers into contact with a surface of the slip sheet;
directing streams of air along an underside of the wing to lift the end portion of the slip sheet off of the printing plate and toward the underside of the wing; and
clamping the lifted end portion of the slip sheet against the underside of the wing.